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Discussion Starter · #1 ·
First off, no - unfortunately this isn't a simple case of cross-gear riding. Even in the middle gears (middle chain ring, center ring on cog) I get MAJOR derailleur rubbing - well, I did. That is until last weekend when my chain finally broke 2 miles into the ride...

I built my bike from scratch with all individual parts that seemed to be of mid or slightly higher grade performance. Now I am thinking I will just buy a pre-fab stock bike from now on, due to what seems like compatibility issues, etc.

Here's my setup:

Giant NRS, 2004 (bought frame only, new, this year)
Fox Float R shock
Marzocchi Fork, 33 tst
Shimano XT/Deore Front and Rear Derailleurs
Rear Cog is Shimano HG II Glide
Crank set - Shimano SLX 600 series
Shifters - SRAM Attack shifters, 8 speed

My entire drive train is 8x3 speed, and its hard to find shifters for an 8 speed. Price Point sold me SRAM Attack shifters for 8 speed, listed them at 2:1 shimano pull ratio (?) and says that they are compatible with Shimano derailleurs. Can anyone else confirm this?

The SRAM shifters work very smoothly with the 8 speed rear shimano deore/XT derailleur, but the shimano XT front derailleur has been rubbing constantly with the chain, and not always shifting smoothly. Took it back to the shop twice, both times they said it was fine (sure, it shifts smoothly on the bike stand, but when presure is applied during actual riding it seems no matter what gear combo (front/back) I use, there is ALWAYS rubbing.)

Any suggestions? I do notice that the cable to the front derailleur is more loose than on my previous bike, a giant yukon 2003, but wouldn't this have been the first thing the bike shop would have looked at?

Thanks for reading this long question, any feedback would be awesome!

Thanks,

-Brian
 

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Discussion Starter · #2 ·
So I guess I have 3 questions -

Does anyone have experience using SRAM and Shimano components together?

What is the likelihood that the front derailleur is just not adjusted properly? Can poor cable tension have such a major effect on chain rubbing?

And the bottom bracket with the SLX 660 crank seems to come out about an inch extra on each side - any chance this is misaligning the chain line and requires larger than usual clearance of the front derailleur as a result?
 

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do you know how to tune a FD? does the shop know? they sound incompetent. use google to find out how to do a front derailuer adjustment. the slx crank is not supposed to move side to side. loosen the pinch bolts and pull out the stopper plate and retighten the preload bolt and pinch bolts. sounds like you dont know what you are doing
 

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Discussion Starter · #4 ·
"...sounds like you don't know what you are doing"

Ummm...basically, thats why I am on the forum :madman:

I'm just surprised the shop missed this ... twice! (they're also the ones that assembled the bike).

Long and short of it is - should there be any reason my SRAM attack 8 speed retarded shifters (R) don't work with a shimano XT F/D???

Thanks - go easy on this novice! Also, the SLX crank isn't moving, its just got a massive bottom bracket that seems to push the large 3 ring crank out further from the frame, thus pulling the chain line away from the frame slightly. There was an article in MTB awhile ago about screwy chainlines being pulled from the frame and the energy that is lost as a result.

So, I'm thinking maybe a chain pulled away from the frame, a loose FD and possible incompatibility with the shimano f/d and sram shifters are causing the problem?

any ideas fellas?

don't know what I'm doing,

-B in SD
 

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giant523 said:
"...sounds like you don't know what you are doing"

Ummm...basically, thats why I am on the forum :madman:

I'm just surprised the shop missed this ... twice! (they're also the ones that assembled the bike).

Long and short of it is - should there be any reason my SRAM attack 8 speed retarded shifters (R) don't work with a shimano XT F/D???

Thanks - go easy on this novice! Also, the SLX crank isn't moving, its just got a massive bottom bracket that seems to push the large 3 ring crank out further from the frame, thus pulling the chain line away from the frame slightly. There was an article in MTB awhile ago about screwy chainlines being pulled from the frame and the energy that is lost as a result.

So, I'm thinking maybe a chain pulled away from the frame, a loose FD and possible incompatibility with the shimano f/d and sram shifters are causing the problem?

any ideas fellas?

don't know what I'm doing,

-B in SD
Check the chain line, stand at the rear of the bike and eyeball down the chain with the front in the middle ring and the back in the middle ring, is it more or less straight....

might be out on gear, but not more...

Take the chain off the front rings, spin the cranks to they glide nice and smooth???

Try to wiggle the crank arms side to side? BB is probably good.

Eyeball the FD cage is it parrallel to the chain rings....

Eye ball the FD cage as you shift up from middle to big chain ring (easier with the chain off), it should just miss the big ring by a mm or so.

Adjust the FD cable tension...

Everything should be fine...

Sit on the bike does the FD rub if so adjust the chain tension a little looser...
 

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Discussion Starter · #6 ·
These are great tips! Will check these and see what I find. The crank and BB setup are all brand new, so its probably an issue with the either something loose and/or the FD.

Thanks again!
 

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Discussion Starter · #9 ·
Vmax911 said:
Also, make sure you are using the correct bottom bracket spacers for your frame.
Exacto. Just got back from the shop and this is exactly what the problem was!

Apparently, there are two different sizes a bottom bracket usually comes in ??? My 2004 giant nrs frame has a 68 mm bracket and so spaceres were used to make up the difference of a 72 mm crank - the SLX - but ended up pushing the crank away from the frame so as to off set the chainline and rub up on the derailleur.

Anyhow, the problem was solved quite quickly and for the first time ever, I'm back on the trail with my custom bike without any rubbing whatsoever! Its almost weird...

Thanks to everyone for their help!!!
 
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